Field of the Disclosure
The disclosure relates to optical systems and more particular, the disclosure relates to a laser beam delivering system capable of transmitting a non-circular light beam emitted by a likewise shaped light source to the desired location and with the desired intensity.
Background of the Disclosure
Up until recently the core geometry of fiber optics has almost exclusively been circular. With new geometrical possibilities differing from a circular design, current fiber optic cables are not only transporting the laser light to the work piece, but can also take an active part in the system design reducing the need for beam shaping optics. For example, a fiber core with a square cross-section delivering a square beam is attractive in various high power applications such as welding and heat treatment applications because it processes the material more uniformly as it moves laterally along the surface compared to a circular beam.
Referring to FIGS. 1A-1D, one of the known beam transmitting schemes includes a pigtailed optical isolator 10. Isolators are optical devices that allow light to be transmitted in one direction only. They are most often used to prevent back reflected light from entering the source. Particularly, but not exclusively, isolator 10 is important when used in high power pulsed fiber laser systems with a master oscillator/power amplifier (“MOPA”) configuration which is very sensitive to high power backreflected light.
Referring to FIG. 1B, isolator 10 includes a housing 12 provided with, among others, a fiber connector 14 at its upstream end and a telescope 16 at its downstream end. The connector 14 receives a delivery fiber 15 including a cladding, and a core 26, which can have any cross-section differing from a circular one, such as a square cross-section shown in FIG. 1C. The fiber 15 delivers amplified light to isolator 10 where the light is first collimated at the input of housing 12 by a lens assembly 18. The collimated beam then propagates in free space through the core of the isolator (not shown) and is eventually magnified by telescope 16 which includes a plano-concave negative lens 20 mounted close the output end of housing 12, and a plano-convex positive lens 22 mounted to the telescope's output end. Seemingly a square-shaped image of core 26 would appear on a workpiece placed in a focal plane of F-theta lens 24. However, it is not the case, as disclosed below.
FIG. 1D illustrates the circular image of core 26 on the workpiece located within a Rayleigh range (“RR”) 28 and substantially coinciding with a waist 30 of the output laser beam. The desired, square-shaped core image is formed in a plane spaced from waist 30 of the beam with the latter being the highest optical intensity region. Yet, as discussed above, both the square image and highest intensity of the beam incident on the workpiece, which is located in a focal plane, are often required for effectively performing the task at hand.
A need therefore exists for an imaging optical system delivering a laser beam with a non-circular cross-section fiber on the workpiece to be processed with the desired intensity.
Another need exists for an imaging optical system operative to invariably place the image of a non-circular fiber core within the RR of the emitted laser beam.
Still a further need exists for a kit including a pigtailed optical component and imaging system which are configured to detachably couple to one another so as to obtain a non-circular image of the likewise shaped fiber core on a workpiece located within the RR.
Another need exists for pigtailed bulk optics provided with an optical system which is operative to focus an image of the non-circular fiber core with the desired maximum intensity on a workpiece located within the RR of the laser beam.
These needs are met by this disclosure as briefly disclosed immediately below.